Chs cha

ABSTRACT

WHEREIN Z3 IS A TROPONOID SUBSTITUENT ON THE CYCLOHEPTATRIENE RING SAID SUBSTITUENT BEING A MEMBER SELECTED FROM THE GROUP CONSISTING OF A LOWER ALKYL (C1-C4) GROUP, A HALOGEN ATOM, A LOWER ALKOXYL GROUP, AN ARYL GROUP, AN ALKYLARYL GROUP AND A CONSISTING OF AN OXYGEN ATOM AND SELECTED FROM THE GROUP CONSISTING OF AN OXYGEN ATOM AND A N-H GROUP; Z2 IS AN ORGANIC SUBSTITUTED OR UNSUBSTITUTED ATOMIC GROUP NECESSARY TO COMPLETE A 5 OR 6 MEMBERED HETEROCYCLIC RING SELECTED FROM THE GROUP CONSISTING OF THE OXAZOLINE SERIES, OXAZOLE SERIES, BENZOXAZOLE SERIES, NAPHTHOXAZOLE SERIES, THIAZOLINE SERIES, THIAZOLE SERIES, BENZOTHIAZOLE SERIES, NAPHTHOTHIAZOLE SERIES, SELENAZOLE SERIES, BENZOLSELENAZOLE SERIES, NAPHTHOSELENAZOLE SERIES, 2-PYRIDINE SERIES, 4-PYRIDINE SERIES, 2-QUINOLINE SERIES, 4QUINOLINE SERIES, IMIDAZOLE SERIES, BENZIMIDAZOLE SERIES, AND NAPHTHOIMIDAZOLE SERIES; R IS A MEMBER SELECTED FROM THE GROUP CONSISTING OF A LOWER ALKYL GROUP, A HYDROXY (LOWER) ALKYL GROUP, A LOWER ALKOXY ALKYL GROUP, A SULFO (LOWER) ALKYL GROUP, A CARBOXY (LOWER) ALKYL GROUP, AN ACETOXY (LOWER9 ALKYL, A VINYL METHYL GROUP, AN ARALKYL GROUP, AND A SULFO ARALKYL GROUP; L1 AND L2 ARE A GROUP FROM THE METHINE SERIES, SAID L2 CAPABLE OF FORMING A METHYLENE CHAIN TOGETHER WITH SAID R GROUP; X IS AN ANION AND M AND N EACH IS 0 OR 1, PROVIDING THAT N IS 0 WHEN THE DYE FORMS AN INTRAMOLECULAR SALT, SAID DYE BEING PRESENT IN A SENSITIZING AMOUNT.   Z3-1,3,5-CLCLOHEPTATRIENE   17. A DIRECT POSITIVE SILVER HALIDE PHOTOGRAPHIC EMULSION COMPRISING FOGGED SILVER HALIDE GRAINS AND AT LEAST ONE DYE OF THE FORMULA:   1,6-(-Z1-CO-C(-L1=L2-C&lt;(=(CH-CH)=N(+)(-R)(X(-))N-Z2-))=),

United States Patent Oflice Re. 28,208 Reissued Oct. 22, 1974 Int. Cl. otisc 1/36 us. on. 96-101 16 Claims Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

ABSTRACT OF THE DISCLOSURE A direct positive silver halide emulsion comprising at least one dye of the formula:

wherein Z is an organic substituted or unsubstituted atomic group necessary to complete a cycloheptatriene ring, which may be optionally substituted with a troponoid compound; Z is an oxygen atom or NH; Z, is an organic substituted or unsubstituted atomic group necessary to complete a 5 or 6 membered heterocyclic ring; R is a member of the alkyl series selected from the group consisting of lower alkyl, hydroxy (lower) alkyl, lower [alkoxy] alkoxyalkyl, sulfo(lower) [alkoxy] alkyl, carb0xy(!0wer)alkyl, ace!oxy(l0wer)alkyl, vinyl methyl, aralkyl sulfo aralkyl; L and L are a group from the methine series, said L capable of forming a methylene chain together with said R; X is an anion, and m and it each is 0 or 1, providing that n is 0 when the dye forms an intramolecular salt, and a photographic light-sensitive element formed from said emulsion. The present invention also extends to the dyes themselves and a process for preparing the same.

FIELD OF THE INVENTION The present invention relates to a silver halide photographic emulsion and particularly to a direct positive photographic emulsion containing a novel dye.

DESCRIPTION OF THE PRIOR ART When a silver halide light-sensitive material is exposed to light in a wave length region sensitive to the material and then developed, the image density is increased with an increase in exposure, thus reaching a maximum value. When the exposure amount increases, the image density is reduced again and finally, a reversal image is obtained. This phenomenon is generally termed solarization.

It has also been known that in some silver halide emulsions which are fogged optically or chemically, a similar reversal phenomenon by light is observed. Hereinafter, such a silver halide emulsion is called the direct positive silver halide photographic emulsion."

In general, the reversal sensitivity of the direct positive silver halide emulsion is increased by the addition of a dye to said emulsion. However, sometimes when this is done, the maximum density (D [See Mees, The Theory of the Photographic Process, Revised Ed. (p. 250) or 3rd Ed. (pp. 149-163)], is lowered and the contrast thereof is reduced, whereby a sufficient image cannot be obtained.

Thus, it is extremely important when producing direct positive light-sensitive materials to maintain a definite or constant maximum density to, increase the sensitivity.

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a direct positive silver halide photographic emulsion capable of maintaining a definite maximum density and providing a high sensitivity.

Accordingly, the object of this invention is attained by adding to the direct positive silver halide photographic emulsion, a dye of the Formula I:

L L r "Zr cH -cH:N+(X-)- z (I) wherein Z represents an atomic group necessary to complete the cycloheptatriene ring. The group represented by Z may also be substituted by a substituent known as a troponoid compound, such as, an alkyl group having 1-4 carbon atoms, such as a methyl group, an isopropyl group, etc.; a halogen atom, such as a chlorine atom, a bromine atom, etc.; an alkoxyl group such as a methoxy] group, etc.; an aryl group such as a naphthyl or phenyl group, a tolyl group and a nitrophenyl group, etc.

Z, represents 0 or N--H.

2,, represents an atomic group necessary to complete a S-membered or 6-membered heterocyclic ring. Illustrative of the heterocyclic rings represented by Z, are those of the oxazoline series, oxazole series, benzoxazole, naphthoxazole series, thiazoline series, thiazole series, benzothiazole series, naphthothiazole series, selenazol series, benzoselenazole series, naphthoselenazole series, 2- pyridine series, 4-pyridine series, Z-quinoline series, 4-quinoline series, imidazole series, benzimidazole series, naphthoimidazole series and the like.

The heterocyclic ring (which may comprise a heterocyclic ring per se or a benzene ring condensed with a heterocyclic ring) may be substituted by known substituents in the field of sensitizing dyes such as an alkyl group (C,-C,), aryl group (phenyl or naphthyl), hydroxyl group, alkoxyl group (C -C halogen atom (Cl, Br, F and I), and nitro group.

R represents a group of the alkyl series, such as a methyl group, ethyl group, n-propyl group, B-hydroxyethyl group, B-methoxyethyl group B-acetoxyethyl group,

B-carboxyethyl group, -sulfopropyl group, c-sulfobutyl group, vinylmethyl group, benzyl group, phenethyl group, p-sulfophenethyl group, etc.

L and L represent a group of the methine series, e.g., a methine group or a methine group having a substituent such as a methoxyethyl group, ethoxyethyl, carboxyethyl and hydroxyethyl. In addition, L may form a methylene chain together with R.

3 X represents an anion such as halogen, perchlorate, ptoluene sulfonate, benzene sulfonate, thiocyanate, methyl sulfate, ethyl sulfate, etc., and

m and n respectively, represent 0 or 1, providing that n is 0 when the dye forms intramolecular salt. 5

A general method for synthesizing the dye of the present invention is briefly described below:

The dye represented by the above-mentioned general Formula I may be obtained by reacting a compound represented by the general Formula II: 10

and a heterocyclic quaternary ammonium salt represented by the following general Formula III:

= r R 2T6 CH/mCIhOUu (In) in acetic anhydride under heating.

The definitions of Z, Z 2;, R, X, m and n in general Formulas II and III are the same as provided for general Formula I.

The compounds of general Formula II may be easily produced by one skilled in the art based on the descriptions in Daiyuki Kagaku (Grand Organic Chemistry), vol. 13, Non-Benzenie Aromatic Cyclic Compounds, published by Asakura Book Co.

The compounds of Formula III may be prepared according to the description given in the text Chemistry of Heterocyclic Compounds," vol. 18 (1964).

The preferred embodiments illustrative of the dyes to be used in the present invention are those shown below. However, the dyes to be used in our invention are not limited to these exclusively.

Dye I 0 N I I- O CZHI O Dye II S OH=OH N Q- I 0 sHl Dye III.. S

Dye IV...

CH=CN E I zHl Dye V..---

CH=CH N-CzHs Dire 0 CH=CH +N I- 2H| N H A MBOH' max. O 498 mp. CH=CH H N I 0 $3115 CH=CN CH=CH TABLE-Continued Dye VII... 1 S 542 m CH=CII .N O 2H6 Dye VIII. S S 543 m 0H=CH- CH=C H /& I N

0 (CIIQ)1SO, -0 (Hfl) S0fl J\ J\ Dye IX.. /Sc 545 mp.

CH=CH N +3: Br 0 HuCHzCOOH Dye X..... C2H|0CHa 520111 I f CH=C N I H Dye XL... 534 mp.

CH=CH 0 N l H Dye XII..- 5 E 546 CH=CII- N-CaH:

1 Dye XIIL'; 0H: OH: x MPOH max. m

CH=CH I \fi/ I.

\N A Dye XIV CH; CH MBOII max.

A procedure for producing the dyes applicable to the present invention will be described below.

Synthesis 1 (Dye I) 2-[2-(1-oxaazulane-2-one-3-yl)vinyl]-3-ethylbenzoxaziolium iodide.To 1 ml. of acetic anhydride were added 30 mg. of 3-formyl-l-ozaazulanone and 60 mg. of 3-ethyl-2-methylbenzoxazolium iodide. The mixture was heated to 135 C. for 30 minutes on an oil bath. The crystals formed were collected and washed with a large amount of hot ethanol, 40 mg. of a dark red crystal having a melting point of 201 C. was obtained.

Synthesis 2 (Dye VII) 2[2-(l-azaazuian-2 one-3-yl)vinyl]-3-ethylbenzothiazolium iodide.-To 3 ml. of acetic anhydride were added 150 mg. of 3-formyl-l-azaazulanone and 280 mg. of 3-ethyl-2-methylbenzothiazolium iodide. The mixture was heated to 135 C. for 30 minutes on an oil bath. When the crystals thus deposited were washed with a large amount of hot methanol, 400 mg. of a dark purple crystal having a melting point of 261 C. was obtained.

It is astonishing that although the dye represented by the general Formula I mentioned above shows no sensitizing effect (in other words, reduces the sensitivity in usual negative type photographic emulsions) it exhibits an excellent sensitizing effect to a direct positive silver halide photographic emulsion.

The direct positive silver halide photographic emulsion containing the dye represented by Formula I should exhibit a sensitivity which is high and maintain a maximum density of the photographic emulsion almost identical to that of the photographic emulsion absent the dye.

In addition, the dye represented by Formula I to a direct positive photographic emulsion, should maintain a low minimum density.

Usually, it is preferred to add the dye represented by Formula I to the silver halide photographic emulsion as a solution. In this regard, suitable solvents for the dye solution may comprise water, methanol and ethanol.

The efiective amount of the dye to be added to the direct positive photographic emulsion ranges from mg. to l g. and preferably, from 100 mg. to 500 mg./kg. of emulsion.

The silver halide photographic emulsion to be used in the present invention may be fogged to the maximum density by light or the addition of a chemical fogging agent. If a chemical fogging agent is employed, it should be one which fogs silver halide without impairing the photographic emulsion. illustrative of these are thiourea dioxide, stannous chloride, formaldehyde, or hydrazine.

Further, the silver halide emulsion to be used in this invention may be fogged by addition of a combined chemical fogging agent and a gold salt.

Subsequent to the fogging operation of the silver halide emulsion, additional additives, such as a coating aid or a hardening agent may be incorporated in the photographic emulsion. Also, if desirable, a color coupler may be incorporated in the silver halide photographic emulsion.

The pH and the pAg of the photographic emulsion are then adjusted and after adding the dye represented by the Formula I to the photographic emulsion, the emulsion is stirred and applied to a suitable support. As the suitable support, there may be employed, a synthetic resin film, such as a cellulose derivative film or a polyethylene terephthalate film, a glass sheet, a baryta-coated paper, a synthetic paper and a laminated paper.

A better understanding of the present invention will be attained from the following examples, which are merely illustrative and not limitative of the present invention:

Example l.-Aqueous solutions of potassium bromide and silver nitrate were added simultaneously to an aqueous gelatin solution and the mixture was stirred vigorously for 45 minutes at a temperature of 60 C., to form silver bromide and after adding thiourea dioxide and potassium chloroaurate, the mixture was warmed for 20 minutes. Thereafter, the silver halide was sedimented by :adding a sedimentation agent and after dispersing the silver halide thus precipitated and washing it twice with water, the silver halide was added and redispersed in an aqueous gelatin solution containing 7.5% by weight of gelatin.

The emulsion was divided into several parts and after adding the dye represented by the general Formula I to each of the divided emulsions, the emulsion was applied to a cellulose acetate base and then dried.

The sample thus produced was exposed by means of a sensitometer and developed for 2 minutes at 20 C., using a developing liquid having the composition shown in Table 1.

TABLE 1 G. Metol 3.1 Hydroquinone 12 Sodium suifite 45 Anhydrous sodium carbonate 67.5 Potassium bromide 1.9

Water to make 1 liter.

TABLE 2 Amount of dye (mg.fkg.- Relative D when Dun... when emulsion) sensitivity not exposed exposed None (control) 1 (12.9 1.59 1. 46 Dye VI (400) 445 1. 48 0. 3i Dye VIII (400) 214 1. 51 0. 62 Dye XI (400). 99 1. 41 0. Dye X11 (400)... 301 1. 52 0. 73

l Pinacryptol yellow.

Example 2.-An aqueous solution of potassium bromide and silver nitrate were added simultaneously to an aqueous gelatin solution. The mixture was stirred for 45 minutes at 60 C., to form silver bromide. Then, potassium iodide (0.6 mole percent of silver nitrate) was added to the emulsion and the emulsion was ripened for 40 minutes.

After the ripening was completed, hydrazine dihydrochloride and potassium chloroaur-ate were added to the emulsion, the mixture being warmed for 16 minutes at 45 C. Subsequently, the silver halide was precipitated by adding a flocculating agent thereto. The silver halide thus precipitated was recovered, washed twice with water and then dispersed in an aqueous gelatin solution containing 7.5% by weight of gelatin.

The silver halide photographic emulsion thus prepared was divided into several parts. After adding the dye represented by Formula Ito each of the divided photographic emulsions, the mixture was stirred and the silver halide emulsion was applied to a cellulose acetate film and dried. The sample thus dried, was exposed by means of a sensitometer and developed for 2 minutes at 20 C., using a developing liquid having the composition shown in Table l and described in Example 1. Then, the sample was fixed, washed with water and dried. After processing, by measuring the optical density of the sample by means of a densitometer, the characteristic curve was obtained. The results thus obtained are shown in Table 3.

Furthermore, almost the same results were obtained by repeating the same procedure using Dyes (III), (VII), (IX) and (X) shown above.

Example 3.An aqueous solution containing 70 gms. of potassium bromide and 6 gms. of sodium chloride as well as an aqueous solution containing 100 gms. of silver nitrate were added simultaneously to an aqueous gelatin solution containing 10% by weight of gelatin. The mixture was reacted at a temperature of 50 C., to form a fine grained silver halide. Then, after adding 1 gm. of potassium iodide and 40 gms. of gelatin thereto, the mixture was adjusted to a pH of 9.5 with sodium carbonate. Thereafter, to said emulsion was added ml. of an aqueous solution containing 1% by weight of hydrazine dihydrochloride. The emulsion was ripened for 40 minutes to form fog-nuclei. Then, the emulsion was adjusted to a pH of 60 by the addition of (by weight) of citric acid, cooled and washed with water.

The silver halide photographic emulsion thus produced was divided into several parts. After adding the dye represented by Formula I to each of the divided photographic emulsions and stirring the mixture, the silver halide emulsion was applied to a cellulose acetate and dried. The sample thus dried was exposed by means of a densitometer and developed for 2 minutes at C., using developing liquid having the composition shown in the Table 1 and described in Example 1. Then, the sample was fixed, washed with water and dried. After processing, by measuring the optical density of the sample with a densitometer, the characteristic curve was obtained.

The results thus obtained are shown in Table 4.

Dyes XIII and XIV exhibit the same properties as shown above for those dyes already enumerated.

Though the present invention has been adequately described in the foregoing specification and examples included therein, it is readily apparent that various changes and modifications may be made without departing from the scope thereof.

What is claimed is:

[1. A direct positive silver halide photographic emulsion comprising fogged silver halide grains and at least one dye of the formula:

nor).-

wherein Z, is a troponoid substituent on the cycloheptatriene ring said substituent is a member selected from the group consisting of lower alkyl (C -C halogen, lower alkoxyl, aryl, alkylaryl and nitroaryl; Z is an oxygen atom or N-I-I; Z is an organic substituted or unsubstituted atomic group necessary to complete a 5 or 6 membered heterocyclic ring selected from the group consisting of the thiazole series, naphtholthiazole series, selenazole series, benzolselenazole series, naphoselenazole series, Z-pyridine series, 4-pyridine series, 2-quinoline series, 4-quinoline series, imidazole series, benzimidazole series and naphthioimidazole series; R is a member of the alkyl series selected from the group consisting of lower alkyl, hydroxy (lower) alkyl, lower alkoxy, sulfo (lower) alkoxy, vinylmethyl, aralkyl and sulfo arakyl; L and L2 are a group from the methine series, said L capable of forming a methylene chain together with said R; X is an anion and m and 11 each is 0 or 1, providing that n is 0 when the dye forms an intramolecular salt, said dye being present in a sensitizing amount] 2. The emulsion of claim [1] 17, wherein said dye is a member selected from the group consisting of:

fl 011:]; \N

3. The emulsion of claim [1] I 7, wherein said silver halide photographic emulsion is fogged to the maximum density by light.

4. The emulsion of claim [1] 17, wherein said silver halide photographic emulsion is fogged to the maximum density by the addition of a chemical fogging agent.

5. The emulsion of claim 4, wherein said chemical fogging agent is a member selected from the group consisting of thiourea dioxide, stannous chloride, formaldehyde and hydrazine.

6. The emulsion of claim [1] 17, wherein said ha'lide photographic emulsion is fogged by the addition of a combination of a chemical fogging agent and a gold salt.

7. An emulsion as claimed in claim [1] I7, wherein an amount of the dye to be added to the emulsion ranges from 10 mg. to l gm./kg of emulsion.

8. A photographic light-sensitive element comprising a support having thereon at least one layer containing the direct positive silver halide photographic emulsion of claim [1] I7.

9. The emulsion of claim [1] 17, wherein the lower alkyl (C C,) troponoid substituent is a member selected from the group consisting of methyl and isopropyl.

10. The emulsion of claim [1] 17, wherein the halogen troponoid substituent is a member selected from the group consisting of chlorine and bromine.

11. The emulsion of claim [1] 17, wherein the lower alkoxyl troponoid substituent is methoxyl.

12. The emulsion of claim [1] 17, wherein the aryl troponoid substituent is a member selected from the group consisting of naphthyl and phenyl.

13. The emulsion of claim [1] 17, wherein the alkylaryl troponoid substituent is tolyl.

14. The emulsion of claim [1] 17, wherein the nitro aryl troponoid substituent is nitro phenyl.

15. The emulsion of claim [1] 17, wherein L, and L] are members selected from the group consisting of methine, methoxyethyl methine, ethoxyethyl methine, carboxyethyl methine and hydroxyethyl methine.

16. The emulsion of claim 7, wherein the amount of dye to be added to the emulsion ranges from mg.500 mg./kg. of emulsion.

17. A direct positive silver halide photographic emulsion comprising fogged silver halide grains and at least one dye of the formula:

wherein Z; is a troponoid substituent on the cycloheptatriene ring said substituent being a member selected from the group consisting of a lower alkyl (C -C group, a halogen atom, a lower alkoxyl group, an aryl group, an alkylaryl group and a nitroaryl group; Z; is a member selected from the group consisting of an oxygen atom and a N-H group; 2: is an organic substituted or unsubstituted atomic group necessary to complete a 5 or 6 membered heterocyclic ring selected from the group consisting of the oxazoline series, oxazole series, benzoxazole series, naphthoxazole series, thiazoline series, thiazole series, benzothiazole series, naphthothiazole series, selenazole series, benzolselenazole series, naphthoselenazole series, Z-pyridine series, 4-pyridine series, Z-quinoline series, 4- quinoline series, imidazole series, benzimidazole series, and naphthoimidazole series; R is a member selected from the group consisting of a lower alkyl group, a hydroxy (lower) alkyl group, a lower alkoxy alkyl group, a sulfo (lower) alkyl group, a carboxy (lower) alkyl group, an acetoxy (lower) alkyl, 0 vinyl methyl group, an aralkyl group, and a sulfo aralkyl group; L and L are a group from the metlhine series, said L capable of forming a methylene chain together with said R group; X is an anion and m and n each is 0 or 1, providing that n is 0 when the dye forms an intramolecular salt, said dye being present in a sensitizing amount.

References Cited Ishikawa et a1.: Seven Membered Ring Compounds as a Densensitizing Agent," Bulletin of the Society of Scientific Photography of Japan, No. 18, December 1968, pp. 515.

DAVID KLEIN, Primary Examiner W. H. LOUIE, Ir., Assistant Examiner US. Cl. X.R. 

17. A DIRECT POSITIVE SILVER HALIDE PHOTOGRAPHIC EMULSION COMPRISING FOGGED SILVER HALIDE GRAINS AND AT LEAST ONE DYE OF THE FORMULA: 